On 6 October 2014 13:06, Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> wrote:
> This reverts commit 84be880560fb, which itself reverted my original
> attempt to move x86 from #include'ing .c files from across the tree
> to using the EFI stub built as a static library.
>
> The issue that affected the original approach was that splitting
> the implementation into several .o files resulted in the variable
> 'efi_early' becoming a global with external linkage, which under
> -fPIC implies that references to it must go through the GOT. However,
> dealing with this additional GOT entry turned out to be troublesome
> on some EFI implementations. (GCC's visibility=hidden attribute is
> supposed to lift this requirement, but it turned out not to work on
> the 32-bit build.)
>
> Instead, use a pure getter function to get a reference to efi_early.
> This approach results in no additional GOT entries being generated,
> so there is no need for any changes in the early GOT handling.
>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxx>
> Cc: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
> ---
>
> Gents,
>
> This is a request for testing: I would like to find out if this patch
> fixes Maarten's issue without breaking anything like it did for Josh
> and Linus the first time around.
>
Any takers?
>
> arch/x86/boot/compressed/Makefile | 3 ++-
> arch/x86/boot/compressed/eboot.c | 8 ++++----
> arch/x86/boot/compressed/eboot.h | 16 ----------------
> arch/x86/include/asm/efi.h | 24 ++++++++++++++++++++++++
> drivers/firmware/efi/Makefile | 2 +-
> 5 files changed, 31 insertions(+), 22 deletions(-)
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 0fcd9133790c..7a801a310e37 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -33,7 +33,8 @@ VMLINUX_OBJS = $(obj)/vmlinux.lds $(obj)/head_$(BITS).o $(obj)/misc.o \
> $(obj)/eboot.o: KBUILD_CFLAGS += -fshort-wchar -mno-red-zone
>
> ifeq ($(CONFIG_EFI_STUB), y)
> - VMLINUX_OBJS += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o
> + VMLINUX_OBJS += $(obj)/eboot.o $(obj)/efi_stub_$(BITS).o \
> + $(objtree)/drivers/firmware/efi/libstub/lib.a
> endif
>
> $(obj)/vmlinux: $(VMLINUX_OBJS) FORCE
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index de8eebd6f67c..58ea406f5d60 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -21,8 +21,10 @@ static efi_system_table_t *sys_table;
>
> static struct efi_config *efi_early;
>
> -#define efi_call_early(f, ...) \
> - efi_early->call(efi_early->f, __VA_ARGS__);
> +__pure const struct efi_config *__efi_early(void)
> +{
> + return efi_early;
> +}
>
> #define BOOT_SERVICES(bits) \
> static void setup_boot_services##bits(struct efi_config *c) \
> @@ -285,8 +287,6 @@ void efi_char16_printk(efi_system_table_t *table, efi_char16_t *str)
> }
> }
>
> -#include "../../../../drivers/firmware/efi/libstub/efi-stub-helper.c"
> -
> static void find_bits(unsigned long mask, u8 *pos, u8 *size)
> {
> u8 first, len;
> diff --git a/arch/x86/boot/compressed/eboot.h b/arch/x86/boot/compressed/eboot.h
> index c88c31ecad12..d487e727f1ec 100644
> --- a/arch/x86/boot/compressed/eboot.h
> +++ b/arch/x86/boot/compressed/eboot.h
> @@ -103,20 +103,4 @@ struct efi_uga_draw_protocol {
> void *blt;
> };
>
> -struct efi_config {
> - u64 image_handle;
> - u64 table;
> - u64 allocate_pool;
> - u64 allocate_pages;
> - u64 get_memory_map;
> - u64 free_pool;
> - u64 free_pages;
> - u64 locate_handle;
> - u64 handle_protocol;
> - u64 exit_boot_services;
> - u64 text_output;
> - efi_status_t (*call)(unsigned long, ...);
> - bool is64;
> -} __packed;
> -
> #endif /* BOOT_COMPRESSED_EBOOT_H */
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index 0ec241ede5a2..b2c854a0f5ca 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -159,6 +159,30 @@ static inline efi_status_t efi_thunk_set_virtual_address_map(
> }
> #endif /* CONFIG_EFI_MIXED */
>
> +
> +/* arch specific definitions used by the stub code */
> +
> +struct efi_config {
> + u64 image_handle;
> + u64 table;
> + u64 allocate_pool;
> + u64 allocate_pages;
> + u64 get_memory_map;
> + u64 free_pool;
> + u64 free_pages;
> + u64 locate_handle;
> + u64 handle_protocol;
> + u64 exit_boot_services;
> + u64 text_output;
> + efi_status_t (*call)(unsigned long, ...);
> + bool is64;
> +} __packed;
> +
> +__pure const struct efi_config *__efi_early(void);
> +
> +#define efi_call_early(f, ...) \
> + __efi_early()->call(__efi_early()->f, __VA_ARGS__);
> +
> extern bool efi_reboot_required(void);
>
> #else
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index aef6a95adef5..d8be608a9f3b 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -7,4 +7,4 @@ obj-$(CONFIG_EFI_VARS_PSTORE) += efi-pstore.o
> obj-$(CONFIG_UEFI_CPER) += cper.o
> obj-$(CONFIG_EFI_RUNTIME_MAP) += runtime-map.o
> obj-$(CONFIG_EFI_RUNTIME_WRAPPERS) += runtime-wrappers.o
> -obj-$(CONFIG_EFI_ARM_STUB) += libstub/
> +obj-$(CONFIG_EFI_STUB) += libstub/
> --
> 1.9.1
>
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